The one I put in is all touch screen too, but from my googling my year model car had a weak head unit and not too bad speakers as a rule so changing the head unit made a lot of difference I think I got an 8700 Bt DVD model can't remember the prefix, maybe avh or summat, I presume your head unit would be a much better one than my standard one so probs is speakers

Got a 2007 hawk wrx, shocking sound system until I replaced the head unit with a nice pioneer , I am now more than happy with the sound quality and volume, not in boy racer league obviously but enough to be too loud still, don't know if your car has a simple double din unit, if it has I would start there unless the later cars actually do suffer with rubbish speakers